from the back of the book
The second supplement for Cthulhu Live Second Edition, Lost Souls plunges Keepers and players alike into the darkest corner of the Cthulhu Mythos. The players assume to roles of mortal servants of the alien horrors from beyond space and time. Bending themselves to the will of their unspeakable gods, they commit glorious atrocities and offer foul sacraments to the eldritch powers they serve.
From the incarnate madness of the Church of the Yellow Sign to the psychopathic ritual killers of the Mund-Caprice Family, Lost Souls gives you everything you need to run a live-action horror campaign exploring the black rituals and foul agendas of Mythos cults and conspiracies./ The book includes guidelines for creating and roleplaying "revenants," the mad servants of the Mythos, as well as extensive source material for over two dozen cults and secret societies. Lost Souls also offers information on the shadow organizations that battle the Mythos cults on their own dark terms, including Delta Green and the Catholic Church's Brotherhood of Sleep.